Re: [Exim] [Fwd: mail solution]

> I've been tasked with finding a large mail solution for between 500,000
> and
> 1,500,000 users, and I've been looking at a bunch of commercial
> products,
> namely iPlanet Messaging Server, Intermail KX/MX and Sendmail Pro. I've
> also
> been looking at fully open solutions, and would like to have some
> feedback
> from people who have used this software day-to-day in large
> environments.
>
> The open solution I have foremost in my mind is namely:
>
> Exim 3.20
> Courier IMAP/POP3 server with Maildirs

Sounds like me two and a half years ago. I went with Exim, a hacked qmail
pop3 daemon and (by now) courier imapd, also using maildir. The archives
should contain some articles, where various people described their setup,
as the question came up before.

I use front-end mail exchangers to route mail and run pop/imap proxy
servers, mail box servers that store mailboxes :) and serve pop/imap to
the proxies, as well as output queue servers to deliver remote mails.
Configuration is done with OpenLDAP, replicating from a central master to
database replica servers as well as shell replica servers. Basic building
blocks are Pentium II/III servers with 512 MB RAM, some with local disks,
others with RAIDs, depending on their task. OS is Linux 2.4. The past
has shown that scaling this up to currently almost two million mailboxes
was no problem at all. Load balancing for smtp/pop/imap/ldap is done
with DNS record sets. Quite cheaper and easier than your setup, but
very reliable. Until I upgraded the kernel recently, uptimes were often
a couple hundred days, so I don't worry all too much about fail-over.

Michael